The newly appointed service chiefs have assumed duties in their various military formations.
The new security chiefs were appointed by President Muhammadu Buhari earlier in the week.
They are: Lucky Irabor, a major general, as the Chief of Defense Staff; brahim Attahiru, a major general, as Chief of Army Staff; Auwal Gambo, a rear admiral, as Chief of Naval Staff and Isyaka Amao, an air vice marshal, as Chief of Air Staff.
While Mr Attahiru took charge as the COAS on Thursday, the trio of Irabor, Gambo and Amao assumed duties at the Defense, Naval and Air force headquarters respectively in Abuja on Friday.
President Muhammadu Buhari has asked the National Assembly to confirm their appointment.